Quad Cities IA/IL

Vol. 3, Issue 2, Fall 2006

INSIDE THIS ISSUE: How Does Estimate Rainfall? Jeff Zogg How Does Radar Es- 1 timate Rainfall? The National Weather Service (NWS) uses radar to detect the location and intensity of various Verifying Tornado 1 atmospheric phenomena includ- Warnings ing , rain and snow. You may have also no- ticed that radar can also provide Looking Ahead: El 3 rainfall estimates (i.e., amounts). Niño and the Winter How does radar do that? Con- tinue reading to find out. Outlook

First, rainfall amounts are di- Quad Cities Forecast 4 rectly related to rainfall rates. Office Achieves Top Specifically, the rainfall amount is given by the average rainfall Score for Upper Air rate multiplied by duration over which the rate was measured. COOP Observations 5 For example, an average rainfall rate of 0.50 inches over 3 hours Needed would produce a rainfall amount of 1.50 inches. The same con- Reminders for Snow 5 cept is used with . Recent example of storm total precipitation from our web- Season page (www.crh.noaa.gov/dvn). Rainfall rate and drop size New Climate Web 5 Services From NWS The rainfall rate (R) is dependent in the air and (3) the average Any change in the drop diameter drop fall speed. The rainfall will increase the rainfall rate by Quad Cities upon three things: (1) the drop diameter, (2) the number of drops rate is most sensitive to changes in the drop diameter. (continued on page 2) Probability of a 7 White Christmas Verifying Tornado Warnings Winter Road Condi- 8 Steve Kuhl tions References Did you know that the National occurred, the warning is consid- fied to be correct. A FAR of Weather Service issues tornado ered a “hit” and is included in zero is a perfect score, and a warnings on a county basis and what is called the Probability of low FAR indicates that only a keeps verification statistics for Detection (POD) database. If a few false alarm warnings were Weather Home Compan- these warnings? Whenever a tornado warning is issued and a issued. ion is a semiannual publi- NWS office, including your Quad tornado does not occur, the cation of the National Cities Weather Forecast Office warning is considered a “miss” (WFO), issues a tornado warning, and is included in a False Alarm In addition to POD and FAR, Weather Service office in warning lead times are also the Quad Cities. Contact employees work to identify Rate (FAR) database. A POD whether or not the tornado actu- of 1 is a perfect score, and a tracked. The lead time for a information can be found ally occurred. If a tornado warn- high POD means that most tor- on page 8. ing is issued and verified to have nado warnings issued were veri- (continued on page 3) Page 2 Volume 3, Issue 2 How Does Radar Estimate Rainfall? (continued from page 1)

underway to develop accurate Z-R values for other precipitation types such as snow. ...the radar does not directly measure Radar rainfall estimates (drop size, distribu- The NWS Doppler radar estimates tion or fall speed)...it the rainfall intensity each time it measures the energy scans the sky. The radar then uses returned from a pre- the rainfall intensity-amount rela- tionship mentioned earlier to esti- cipitation target... mate the actual amount of rainfall that fell. Although the NWS Dop- pler radar provides 1- and 3-hour rainfall estimates by default, the Example of a new NWS experimental precipitation analysis radar operator can specify other product that is based on radar data. It is available on the durations as needed. web at: www.srh.noaa.gov/rfcshare/precip_analysis_new.php Two common sources of error exist in rainfall estimates. One is the third power, or cubed. For sensitive to drop diameter. Any when hail is present. Hail tends to example, if the drop diameter change in drop diameter will reflect much higher amounts of doubles, then the rainfall rate increase the reflectivity by the energy back to the radar, leading will increase by a factor of 8. sixth power. For example, if to inflated Z and R values. In That is, 2 3 = 8. Thus, you can the drop size doubles, then the addition, wet snow can also lead see that changes in the drop reflectivity will increase by a to inflated Z and R values because diameter will lead to much factor of 64. That is, 2 6 = 64. it also reflects higher than average For More information larger changes in the rainfall Thus, you can see that reflectiv- amounts of energy back to the On the Web: rate. ity is very sensitive to changes radar. The wet snow error is in drop diameter. sometimes called the “bright band” error because it appears on Target reflectivity and the the radar screen as relatively Radar equation and re- radar equation Reflectivity-rainfall rela- flectivity (NWS) -- higher Z values, when compared tionships to the surrounding lower Z values www.wdtb.noaa.gov/ Unfortunately, the radar does associated with solely liquid pre- courses/dloc/topic3/ cipitation. lesson1/Section2/ not directly measure any of Research has provided us with the above three items. In- equations that show the rela- Section2.html stead, it measures the energy tionship between reflectivity Conclusions returned from a precipitation (Z) and rainfall rate (R). These

Radar equation and re- target. A precipitation target equations are called Z-R rela- Even though the radar can provide flectivity (American Mete- can include a rain drop, snow- tionships. Weather radar then flake or hail stone. The NWS uses these equations to estimate us with rainfall estimates, real- orological Society) -- then uses the radar equation R. Various Z-R relationships time rainfall and weather observa- http:// which expresses the relation- exist. Different relationships tions that cooperative observers amsglos- ship between the returned are appropriate for different and spotters give us are still ex- sary.allenpress.com/ energy and reflectivity of a atmospheric conditions. For tremely valuable. We use the glossary/search? precipitation target. Since all example, some Z-R relation- rainfall measurements to check p=1&query=radar+equation the terms of the radar equation ships are better for non-tropical the accuracy of the radar rainfall except reflectivity are usually showers and thunderstorms estimates. If we notice that the known, the reflectivity can be while others are better for tropi- rainfall estimates are too high or determined. cal environments. The radar too low then we can make adjust- operator must make sure that ments. Also, we can adjust the the radar is using the appropri- radar rainfall estimates in areas Reflectivity (Z) depends on ate Z-R relationship for the where observers report hail. It is two characteristics of liquid given conditions. If the Z-R important that we receive all of precipitation: (1) the number relationship is not appropriate this information as quickly as of drops and (2) the drop di- then the rainfall estimates may possible so that we improve our ameter. Reflectivity is most not be accurate. Research is services. Weather Home Companion Page 3 Looking Ahead: El Niño and the Winter Outlook Barbara Mayes Despite the cold start to fall, the Niño is forecast to persist through the globe might seem far away, ...The NWS is fore- National Weather Service’s the winter and into at least the the effects of the warmer ocean casting a better- Climate Prediction Center is early spring. are far-reaching. Weather pat- than-usual chance forecasting a better-than-usual terns across most of the U.S. chance for a mild winter this change during an El Niño, bring- for a mild winter year across most of the Plains What is El Niño? ing a higher-than-usual chance for this year… and upper Mississippi River the southeastern U.S. to stay cool valley. The winter forecast is The hallmark of El Niño is and the northern and western U.S. based on many factors, but one warmer-than-normal sea surface to stay warm through the winter . major contributing factor is the temperatures in the tropical Pa- developing El Niño. The El cific Ocean. While that part of (continued on page 4)

Verifying Tornado Warnings (continued from page 1) tornado warning is considered occurred in the 36 county service As the Meteorologist in Charge of to be the time between when area in which WFO Quad Cities WFO Quad Cities, I am ex- the warning is issued and when has warning responsibility. The tremely proud of the warning the tornado actually occurs in actual verification statistics for service our office provided to the the warned location. WFO Quad Cities was a Probabil- citizens of eastern Iowa, western, ity of Detection of 84% and a False Illinois, and northeastern Mis- Alarm Rate of 59%. Both these souri during the 2006 severe The 2006 NWS Probability of scores exceeded the national NWS weather season. It is my sincere Detection goal for tornado goals set for the year. Addition- pledge to you that we will remain warnings across the nation was ally, the 2006 NWS national aver- vigilant and continue to safeguard to be correct 76% of the time, age tornado warning lead time goal our public from the threat of se- and the False Alarm Rate goal was 13 minutes. WFO Quad Cities vere weather in the years to come. for these warnings was 75%. tornado warning lead time was 21 During the 2006 severe weather minutes, which exceeded the na- season, 31 confirmed tornadoes tional goal by 8 minutes. ...Both of these scores (POD and FAR for NWS Quad Cities office) ex- ceeded the national NWS goals set for the year... Page 4 Volume 3, Issue 2 Looking Ahead: El Niño and the Winter Outlook (continued from page 3)

Rainfall patterns also change, mostly in the southern states and along the West Coast. In the Quad Cities forecast area, El Niño winters do tend to be warmer than normal, with no clear trend in the amount of precipitation.

What does the winter fore- cast mean?

Climate predictions are made Average Annual in terms of chances of depart- ing from average conditions. Snowfall* Climate forecasts can’t tell what the day-to-day weather will be, but they can use infor- Dubuque: 42.8 mation based on ocean tem- since El Niño does not tend to Climate forecasts are available Cedar Rapids: 28.8 peratures and global flow pat- change the climatology of pre- at the national scale terns to determine parts of the cipitation in the winter in the Moline: 33.8 (www.cpc.ncep.noaa.gov ) and U.S. where changes from usual area. The winter outlook is not locally ( www.weather.gov/ Burlington: 29.1 conditions may occur. In this able to tell how snowy the climate/calendar_outlook.php? case, the winter outlook calls winter might be, because snow- wfo=dvn ). for a higher-than-average fall depends not only on tem-

* Source: NCDC Cli- chance that temperatures will perature and precipitation but be above normal this winter in also development of storm The Local 3-Month Tempera- mate Normals 1971- the Quad Cities forecast area. systems, which cannot be fore- ture Outlooks are a new way to 2000 The precipitation outlook calls cast months in advance . look at how the climate fore- for equal chances of being wet, casts can affect temperatures at near normal, or dry this winter, individual points in the area .

Quad Cities Forecast Office Achieves Average Winter Sea- son Temperature* Top Score for Upper Air John Hasse Dubuque: 20.9 The Quad Cities National These weather parameters are received is a “snapshot” of the Cedar Rapids: 22.2 Weather Service Forecast Of- sent to an office computer atmospheric conditions, and used fice, is one of nearly 100 of- through a transmitter in supercomputers for improving Moline: 24.8 fices across the nation that housed in the pack- forecasts and warnings. Because Burlington: 26.3 launches weather age. Balloons are usually filled this data is so important, your every day throughout the year. with hydrogen gas (the lightest NWS personnel launch balloons In fact, the balloons are re- element), and typically will rise in all types of weather (except *Source: NCDC Climate leased twice a day, at 6 am and to a height of around 20 miles during lightning, of course). 6 pm CDT or 5 am and 5 pm before bursting. A parachute Normals 1971-2000 for CST. A radiosonde attached to the radiosonde meteorological winter— (instrument package) attached brings the “train” safely back to History Dec, Jan and Feb. to the , records tempera- earth. Only about 20% of the ture, relative , pres- “sondes” are found and sent Upper air observations started as sure, direction and wind back to the National Recondi- early as 1749 in Europe with the speed. When aloft are tioning Center in Kansas City, also retrieved, the radiosonde is Missouri. There, they are re- then known as a “rawinsonde”. built and used again. The data (continued on page 6) Weather Home Companion Page 5

COOP NEWS

COOP Observations Needed Bill Elliott

To our Cooperative Ob- ways of radio, across the state. these agencies receive data real servers around the Daven- time. port Weather Office area: Secondly, all of the data, precipi- We need your observa- tation, snow measurements, and We know you are taking the tions . temperatures you record are observations during the early needed for maps that are sent to morning hours each day, now Yes, we do get your monthly the world several times a day. we ask that you please call us forms, and we like how they Each of the parameters listed, is daily with your vital reports. ...Our goal is to get look and that they are on time, accumulated for every reporting We answer the phones 24/7 and every COOP Ob- but we need to hear from you site in the U.S. and maps gener- look forward to hearing from every day. Our goal is to get ated from your data are sent to you any time between the hours server to call us, or every COOP Observer to call every radio and TV station of 6 AM and 8 AM. If you in some other way us, or in some other way get across the U.S. and around the can’t call us during those get your observa- your observation to us in real world. What a great way to get hours, we still need your report. time. the credit you deserve. If you prefer not to call us at tion to us in real our 800 number, we can ar- time ... range for you to report by com- There are several reasons we Thirdly, the data you provide are puter or a toll free phone num- would like to do this, and there important inputs into computer ber data collection system. are several reasons you might models and products that are Precipitation calls are needed want to help get your observa- developed by several national for both rain and snowfall tions to us on a real time basis. agencies on a daily and monthly amounts, from Illinois and basis. For example, the National Iowa. If you have any ques- Drought Monitor and the North tions, please call Mike Zenner, The first and most important Central River Forecast Center Terry Simmons, or Bill Elliott reason is an increased demand count on real-time precipitation at 563-386-3976. for real time data. Your report reports to develop flood guid- would make the daily state ance for all of the rivers across summary of observations that the Midwest, and to determine We look forward to hearing goes out to the rest of the world the onset and end of droughts, from you! at 815 AM every day of the identify precipitation patterns, year. Some of these summaries and evaluate soil moisture. It is are read verbatim over the air- of the utmost importance that

Reminders for Snow Season

Reports of snow fall and snow important for snow measure- inner measuring tube of depth are in great demand each ments to be taken in a consistent the eight-inch manual rain winter. The prime users of manner. gauge. This allows the snow measurements are frozen precipitation to fall schools, businesses, highway into the overflow can for and road departments, insur- Each season before the first more accurate water ance agents, actuaries, media, snow, Cooperative observers equivalent measurements should review instructions for meteorologists, hydrologists, 2. Check the gauge to ensure climate researchers and many measuring snow and prepare gages and snowboards. others. Because demand for (continued on page 6) snow information is high, it is 1. Remove the funnel and Page 6 Volume 3, Issue 2 Reminders for Snow Season (Continued from page 5)

When reporting solid pre- there are no leaks. Take appropriate action if leaks cipitation: are found. More complete information and 3. Put a (s) out and 1. Measure and record snow- specific instructions on how and mark the location(s) with a fall (snow, ice pellets) since where to measure snowfall and flag or some other indicator the previous snowfall obser- winter precipitation, as well as so boards can be found after vation. obtaining water equivalent, can Snow stick meas- a new snow- 2. Determine the depth of be found on the web at the NWS fall. Snowboards should be snow on the ground at the Cooperative Observer website: uring record snow- located in open locations normal observation time. fall in Davenport in (not under trees, or near 3. Measure and record the www.nws.noaa.gov/om/coop/ December 2000. other obstructions). water equivalent of snow- snowguid.htm.

fall since the previous day's observation.

Quad Cities Forecast Office Achieves Top Score for Upper Air (continued from page 4)

use of a kite to carry aloft a were flown. And . With the ad- in 1937, the U.S. Weather vent of hot air and hydrogen Bureau established a net- balloons in the 1780’s, sci- work of upper air stations, entists actually ascended which the National Weather aloft, taking with them Service continues to this day. weather instruments. As you might imagine, this proved to be very dangerous work. Ranked #1 In the meantime, the use of NWS Quad Cities named kites in observing the upper the best upper air site in in the Nation atmosphere continued, and the nation in August by the end of the 1800’s, kite 2006 August 2006 observation stations were established in Europe and in To help improve data qual- the United States. The kites ity, quantity, and availability, carried aloft meteorological an equation is used to rank instruments or upper air station perform- “meteorographs” that re- ance at NWS offices across corded relative humidity, the nation. In August 2006, temperature and pressure on the NWS Quad Cities had a clockwork driven chart the highest ranking upper air recorder. However, a major Inflating weather balloon inside upper air performance in the nation drawback to using kites was building at NWS Quad Cities . ...The upper air pro- with a score of 299.89 out of that they could only reach an 300! The upper air program gram is one of many altitude of a couple of miles. not be analyzed until the plane is one of many in the office in the office where landed. The lack of kites and airplanes to achieve high alti- where we strive for excellence, we strive for excel- The advent of airplanes carrying tudes, operate in any weather helping to bring better forecasts lence... weather instruments from about conditions, and provide real- and warnings to the public, using 1925 to World War II, meant the time data helped create the need a proven method that started

demise of kite observations. Yet, for radio transmission of upper- more than 200 years ago. airplanes could not be flown in air data. In the early 1930’s, bad weather and the data could the first radio-meteorographs or Weather Home Companion Page 7 New Climate Web Services from NWS Quad Cities Example of Informa- Ray Wolf tion Available from Local Much has happened in the last two years with the This new web page is the vehicle with which we distribution of climate information and Coop data. share virtually all climate-related information. Data/Records: Most notable is the addition of new climate prod- Note the tabs on top of the graphic below, which ucts on the web: are used to navigate from topic to topic. Highlights www.weather.gov/climate/index.php?wfo=dvn from some of the tabs/topics are described below. Probability of Snowdepth > 1 Inch on Chirstmas Day

This graphic can be found under “local cli- mate studies”

Observed Weather tion includes pie charts of the probability distribu- . A closer look at a re- tion of temperatures given the CPC outlook gional graphic, shows Observed Weather The tab provides access to the probabilities of a current and archived ASOS-based climate prod- Local Data/Records ucts including the Daily Climate Report, the F6 White Christmas in the

monthly summary, Record Reports, Monthly local area, based on Climate Summaries, and the Regional and State The Local Data/Records tab contains a wealth of climatology. Temp/Precip Tables. When a product is selected, information including graphs of actual and normal the location and timeframe menus update show- temperature, precipitation and snowfall for the ing what information is available. For example, current and past years, local Storm Data reports, Probabilities for indi- the F6 database goes back 5 years and the Daily area freeze dates and probabilities, snow cover vidual cities are avail- Climate Report goes back three months. Note analyses, extreme event web pages, local climate also links to the SPC and NCDC storm report studies conducted by our office, and much more. able. Here are some archives in the bottom left corner. This informa- We have several additional local studies underway examples: tion is available for several decades prior. which will be posted to this page upon their com- pletion. One project nearing completion is on the

changes in local severe weather climatology ∗ Dubuque: 53 % Climate Prediction (tornado and hail days) based on El Nino – La ∗ Cedar Rapids: 47 % Nina. The Climate Prediction tab contains links to the ∗ Moline: 37 % Climate Prediction Center outlooks from week 2 NowData ∗ Burlington: 30 % through 1 year, plus El Nino-La Nina informa-

tion, and the new Local Three-Month Tempera- ture Outlooks (L3MTO). The L3MTO combines The NOWData tab (NOAA’s Online Weather CPC long range outlooks and coop climate data Data) is a real-time portal to the Coop observer and converts the temperature forecast from a (Continued on page 8) large scale down to a single point. This informa- NWS Quad Cities 9050 Harrison Street Davenport, IA 52806

Weather Home Companion

New Climate Web Services NWS Quad Cities 9050 Harrison Street from NWS Quad Cities Davenport, IA 52806 Phone: (continued from page 7) (563) 386-3976 and ASOS data for the current impacts are occurring. You will Winter Road Conditions

year and previous year. You also find access to the National On the web: can select from a number of Drought Monitor on this page. weather.gov/quadcities Illinois: 1-800-452-IDOT menu options to get normals, daily and monthly records, (4368) Editor: David Sheets The Drought Monitor is produced E-mail: monthly averages, daily data, www.dot.il.gov/operations/i and more for all these sites. weekly and assigns a rating to [email protected] drought areas based on a combi- netcond.html Since data is available daily, you can see the value of report- nation of standard objective Contributors: drought indices plus local input ing your Coop data each day. Bill Elliott , Hydro- from a broad range of government Iowa: 1-800-288-1047 or meteorological Technician agencies associated with water 511 John Haase , Meteorologist Drought information services resources. We provide the local Intern have increased beginning in input for eastern Iowa, northwest www.511ia.org Steve Kuhl , Meteorologist-in- 2005. From the left menu on Illinois, and extreme northeast Charge the main web page Missouri through our interactions Barb Mayes , Forecaster (weather.gov/dvn), select with the Corps of Engineers, Missouri: 1-800-222-6400 David Sheets , Forecaster Drought Status under Current USGS, State Cooperative Exten- www.modot.org/road_cond Terry Simmons , Data Conditions . This links to a sion Services, and USDA. This is Acquisition Program Manager page which contains a local another area where daily Coop itions/WinterRoadCondition Ray Wolf , Science Operations drought statement when moder- observer data is extremely help- s.htm Officer ate or greater drought condi- ful, if not critically important in Jeff Zogg , Hydrology Program tions cover a large part of our meeting our mission. Manager area and/or significant drought